Smallpox Fact Sheet

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Smallpox is a contagious disease caused by a virus

Smallpox is caused by the variola virus. In the United States, routine vaccination against smallpox ended in 1972. Although smallpox was eradicated in 1977, there is the possibility that the illness may reappear due to an intentional bioterrorist activity.

Anyone exposed to the smallpox virus may get smallpox. Even people who have been vaccinated for smallpox might become ill, because the duration of protection given by the smallpox vaccine is not fully understood.

The smallpox virus can be easily spread from one person to another after coming into close (within 6 feet) contact with a person who has smallpox. The virus is often contained in the saliva droplets of a person with smallpox.

Initial symptoms of smallpox may be similar to influenza

Symptoms of smallpox include sudden onset of:

  • Malaise
  • fever (temperature 101° F or greater)
  • vomiting and occasional abdominal pain
  • headache
  • severe backache

Two to four days after initial symptoms:

  • rash on face, arms, and legs

Several days later:

  • rash moves to the midsection of the body

Contact your doctor immediately if you develop these symptoms and if you think that you have been exposed to smallpox.

Progression of the rash on the body is key to differentiating smallpox and chickenpox

Generally, the chickenpox rash begins on the covered parts of the body and progresses to the arms, legs, and face while the smallpox rash first appears on the face and other extremities and later moves to the trunk of the body.

There is no specific medical treatment for smallpox infection

There is no known treatment for smallpox, although approximately two-thirds of those infected with this virus have survived previous outbreaks. The smallpox vaccine is sometimes used to lessen symptoms, and may be helpful if given within four days of exposure to someone with smallpox.

Routine smallpox vaccination is not recommended for the general public

If an outbreak of smallpox occurs, doses of the smallpox vaccine may become available through the national drug stockpile maintained by the Centers for Disease Control. Plans are currently in progress to increase the current stockpile of this vaccine.